Material and process for preparing metal for painting



Patented Aug. 11, 1925.

UNITED sures JAMES H; GRAVE-LL, OF ELKINS PARK, PENNSYLVANIA.

MATERIAL AND PROCESS FOR PREPARING METAL FOR PAINTING.

No Drawing.

To all whom it may concern:

Be it known that I, JAMES H. GRAVEIL, a citizen of the United States, residing at Elkins Park, in the county of Montgomery and State of Pennsylvania, have invented a new and useful Improvement in Materials and Processes, for Preparing Metal for Painting, of which the following is a specification.

This invention relates to improvements in the preparation of metal for painting and more particularly to the preparation for painting of metal articles which, due to their size or shape, are not adapted for immersion in a chemical bath but are suscept ible to being brushed, sprayed, scrubbed or similarly treated with a chemical wash.

The object of the invention is to remove dirt, scale, rust and material that causes rust in a simple and effective manner so that when that work is completed the metal will be in a condition suitable for receiving a protective coating of paint or the like. By a slight modification of the invention the material and process fmay be adapted to remove oil in addition to the substances already mentioned from metal surfaces.

Generally stated, the invention consists in applying an acid colloidal Wash, hereinafter more fully described, to the surface of the metal, permitting it to remain for a sufiicient time to act on the metal and produce the desired cleaning effect, then. removing the surplus wash alongwith the products of its action on the metal, and then causing or permitting the metal to dry, thus producing a surface well suited for the reception of paint or other protective coating.

Although any metal etching acid ma be used with more or less success in ma 'ng my acid colloidal admixture or scrubbing Wash, I prefer to use phosphoric acid because it has "rust inhibitive qualities whichare very desirable, therefore I will describe my admixture or colloidal scrubbing wash in connection with phosphoric acid althou h it must be understood that other metal etc ing acids and acid salts, which produce free hydrogen ions in solution, may .be' substituted for phosphoric acid without departing W from the s irit of the invention.

I have 0 served that an acid solution, for example, made by mixing 220- gallons of 85% phosphoric acid and 641 gallons of Application filed January 20, 1923, Serial No. 614,042.

water has a certain speed of cleaning action when metalis dipped into it, but the speed of the cleaning action is greatly reduced when the acid solution is applied as a wash of free hydrogen ions in close proximity with the metal surface of the article but in the case of the application'of the said solution in the form of a wash to an u right metallic surface the film of the was adhering to the upright surface is very thin so that there are comparatively few free hydrogen ions in close proximity with the metal. I have further observed that the addition of 82 pounds of gelatine dissolved in 82- gallons of water to the above mentioned acid solution is productive of peculiar results. In the case of a bath the solution acts slower but in the case of a wash the solution acts uicker because in the first case the gelatine mterferes with the free movement of the hydrogen ions and in the secondcase the gelatine causes a material increase in-the thickness of the film adhering to the upright metallic surface thus increasing the number of free hydrogen ions in close proximity with the metal and this increase in the number of. hydrogen ions more than ofisets the restriction of the free movement of the hydrogen ions with the result that the use of gelatine augments the cleaning activity of the wash on upright surfaces. The genatine may be regarded as a controlling 0'1 retarding agent in acid baths since .it serves to diminish the cleaning 7 activity but in acid washesit is an accelerating agent and augments the cleaning activity, The following is an example of a cleaning material which produces improved results when applied as a wash:

Y Part 1'. Gelatine 82 pounds Water"; "5., 82 gallons p Part2. 85% phosphoric-acid; 220 gallons ater 641gallons Part" 1 is made by'soaking the gelatino? in the water until it softens. The mixture? is then heated to 130" F. untll the gelatineis thoroughly melted when the mixture is added to Part 2 and the admixture thoroughly stirred. T

This forms an excellent cleaner when used according to the process which l have described, but it does not adhere rapidly to an oily surface. To give the cleaner the property of quickly adhering to an oily surface, I add an oil solvent such fusel oil, butyl alcohol or the like, as shown in the following formula:

It will be observed from the above formulas that the elatine which is a hydrophile gwater lovin g) colloid is converted into a soluble colloid (which does not settle out of the admixture, as distinguished from a solid colloid such as clay which does settle out) and remains as such in the admixture.-

, The'process of the invention may be commercially carried out by applying-the described admixture to the metal, as for instance with a brush; allowing it sufiicient time to produce the desired cleaning result, assisting its action with an abrasive during this time if desired; removing what remains of the admixture together with the products of its reaction in any way desired as for example by wiping, blowing off, burning off or washing; and, then permitting or causing the metal to thorough y dry. The metal is then ready to receive the paint or other protective coating.

The inventlon being of a chemical nature I reserve the benefit of the doctrine of equivalents as applied to the construction of Eatents'for such inventions so' that it. will e evident to those skilled in the art that as wood alcohol, denatured alcohol (ethyl alcohol),

eeann modifications and changes may be made in tion of metal for painting which comprises phosphoric acid, colloidal gelatine, and

alcohol.

4. A cleaning agent for use in the preparation of metal for painting which com rises phosphoric acid, colloidal gelatine, and utyl alcohol.

5. The method of preparing upright metal surfaces for painting which consists in washing'it with a metal etching acid in the presence of colloidal gelatine and an oil solvent.

6. The method of preparing an upright metal surface for painting which consists in washing it with phosphoric acid in the presence of colloidal gelatine.

7. The method of preparing upright metal surfaces for painting which consists in washing it with phosphoric acid in the presence of colloidal gelatine and butyl alcohol.

8. The method of preparing an upright metal surface for painting which consists in washing it with a wash comprising phosphoric acid and colloidal gelatine and butyl alcohol, allowing time for the wash to act on the'metal, and removing the remainder of the Wash together with the products of its action on the metal.

9. The method of preparing an upright metal surface for painting which consists in treating it with an admixture of phosphoric acid, colloidal gelatine and butyl alcohol, assisting the action of the admixture by scrubbing with an abrasive, and removing the remainder of the admixture together with the products of its action.

JAll/[ES H; GRAVELL.

ainting which com- 

